When soft tissue tears away from bone, reattachment becomes necessary. Various devices, including sutures alone, screws, staples, wedges, and plugs have been used in the prior art to secure soft tissue to bone.
Recently, various types of threaded suture anchors have been developed for this purpose. Some threaded suture anchors are designed to be inserted into a pre-drilled hole. Other suture anchors are self-tapping.
U.S. Pat. No. 5,964,783 to Grafton et al., the disclosure of which is incorporated by reference herein, discloses a threaded bioabsorbable suture anchor provided with a loop of suture that is insert-molded directly into the suture anchor during manufacturing. The proximal end of the suture anchor body of the '783 patent is provided with a non-threaded hexagonal drive head. The insert-molded suture preferably extends through the entire length of the suture anchor body and exits through the drive head at the proximal end of the anchor to form a loop of suture external to the suture anchor. In this manner, the suture forming the loop is secured effectively to the threaded suture anchor and is prevented from becoming detached from the anchor. However, because the suture anchor of '783 patent is provided with the non-threaded hexagonal head, the threads of the threaded anchor body do not reach the top of the cortical bone when the suture anchor is installed. Thus, the threaded anchor body tends to move up to the bone surface by at least a distance equal to the length of the non-threaded hexagonal head, such that the drive head may become proud to the surface. Moreover, the suture of the eyelet, which is disposed outside the suture anchor in back of the drive head, may abrade the adjacent tissue.
Accordingly, a need exists for an improved threaded bioabsorbable suture anchor which is threaded along the entire length of the anchor body, including the drive head, to improve fixation of the anchor in bone. In addition, a need exists for a bioabsorbable suture anchor having a suture loop that does not extend beyond the drive head and does not abrade tissue.